HardLabs

A2ext

iolo·a2ext·hw/a2ext-carrier/a2ext-carrier.kicad_sch

This repository ships a schematic but no board layout.

About the A2ext PCB

A2ext is an open source RP2040/RP2350 PCB design by iolo, published on GitHub. It is a board, with 11 components from 10 distinct parts.

Its main chip is the WeAct RP2350B V1.0 (prepared module), from the RP2040/RP2350 family. By type, the board carries 3 capacitors, 2 connectors, 2 fuses, 1 module, 1 jumper and 1 diode.

From the project

General purpose Apple II Extension Card using RP2350B

Open a2ext-carrier.kicadpro in KiCad 10. Symbols are project-local and embedded in the schematic. BOM.csv lists component values; footprints not yet specified are deliberate because PCB layout is out of scope. connections.json` is the generated connectivity contract, checked against KiCad's exported netlist.

Revision 0.5 uses A4 landscape with 1.524 mm pin names, wire labels, and values; pin numbers are 1.27 mm and references/notes are 1.778 mm. Symbols and notes are rearranged for printing at actual size; electrical connections are unchanged.

A2ext bill of materials (BOM)

11 components, 10 distinct parts — part numbers from the project's BOM.

QtyPartRefs
1
WeAct RP2350B V1.0 (prepared module)
M1
1
Apple II slot, counter-clockwise numbering
J1
1
Daughterboard IDC20
J2
1
500mA PTC
F1
1
100mA PTC
F2
1
SYNC: OPEN except verified slot 7
JP1
1
SS14
D1
1
100NF
100nF
C8
2
10UF
10uF
C9, C10
1
10K
10k
R4

A2ext design files

The KiCad project lives in the iolo/a2ext repository on GitHub; these links point at the commit this page was built from.

A2ext: common questions

What microcontroller does the A2ext use?

The A2ext is built around the WeAct RP2350B V1.0 (prepared module), from the RP2040/RP2350 family.

How many components are on the A2ext?

11 components, from 10 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.

Where can I download the A2ext design files?

From the iolo/a2ext repository on GitHub, which has the schematic and the BOM; the links under Design files point to each one.

Can I use the A2ext design in my own project?

The repository has no license, so all rights stay with iolo. Use it as a reference, and ask the author before reusing the design.

Can I test firmware for the A2ext without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug RP2040/RP2350 firmware against it before you order a PCB.

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